lunacy: fix "Unsupported file format" toast at startup

[eliandoran]

Description of changes

Whenever the application is started, a toast notification is shown:

“Unsupported file format. Please open a .sketch or image file”

It does not matter if this is a first start (with the Welcome sketch which does load properly), or if there are no sketches to be loaded.

Apparently the issue is the fact that we are running the application from a symbolic link. Running it directly from lib/Lunacy does seem to do the trick. In this case we probably need a wrapper.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[eclairevoyant]

please also update meta.mainProgram accordingly

[eliandoran]

@eclairevoyant, thanks for noticing, I changed the executable's name accidentally and that would have broken a few things.
It should be OK now.